Polarization-Dependent Plasmonic Transmission of Subwavelength Metasurfaces Resonating at D-Band Frequencies

Plasmonic metasurfaces with engineered subwavelength geometries enable extraordinary electromagnetic transmission and have attracted enormous attention for applications in nanofabrication, sensing, imaging, and wireless communications. At terahertz D-band (0.1-0.3 THz) frequencies, where ultra-broadband, short-range communication systems are emerging, achieving efficient wave control remains a critical challenge due to material losses and scalability limitations.

We present a systematic study of resonant transmission behaviors of plasmonic arrays consisting of subwavelength rectangular apertures, for the first time to our knowledge, at D-band communication frequencies. Terahertz time-domain spectroscopy (THz-TDS) was employed to characterize the amplitude and polarization response of the array samples with varying aperture widths. Numerical simulations using CST Microwave Studio were carried out to analyze the field distributions and underlying resonance mechanisms. Both experimental measurements and numerical simulations demonstrate that the transmission properties are highly sensitive to aperture width and polarization orientation. For the x-polarized incidence, a dominant resonance peak near 0.165 THz was observed, with transmission amplitude increasing with aperture width. Extraordinary transmission exceeding unity, when normalized to aperture area, was attributed to the combined excitation of dipolar localized surface plasmons, surface plasmon interactions, and non-resonant scattering. In contrast, the y-polarized incidence produced sharper resonances and stronger transmission, particularly at an aperture width of 350 μm. Field distribution analysis confirmed the polarization-dependent resonance strength and its attenuation at narrower apertures.

Our findings provide new insights into the modal coupling and extraordinary transmission mechanisms of subwavelength terahertz metasurfaces. The demonstrated tunability of resonance frequency and field confinement highlight their potential in developing compact, reconfigurable, and efficient frequency-selective components such as filters, reflectors, and modulators for next-generation short-range, high-data-rate terahertz wireless communication systems.